LABYRINTHULIDEA

This article appears in Volume V16, Page 35 of the Encyclopedia Britannica.

Encyclopedia Britannica - Main :: KRO-LAP

LABYRINTHULIDEA , the name given by Sir Ray Lankester (1885) to Sarcodina (q.v.) forming a reticulate plasmodium, the denser masses united by fine pseudopodical threads, hardly distinct from some Proteomyxa, such as Archerina.
This is a small and heterogeneous group. Labyrinthula, discovered by L. Cienkowsky, forms a network of relatively stiff threads on which are scattered large spindle-shaped enlargements, each representing an amoeba, with a single nucleus. The threads are pseudopods, very slowly emitted and withdrawn. The amoebae multiply by fission in the active state. The nearestapproach to a " reproductive " state is the approximation of the amoebae, and their

separate

SEPARATE

encystment in an irregular heap,
Labyrinthulidea.
several cells which have lost their definite spindle-shaped contour. s, Corpuscles which have become spherical and are no longer moving (perhaps about to be encysted).
4. A single spindle cell and threads of Labyrinthula macrocystis, Cienk. n, Nucleus.
5. A group of encysted cells of L. Macrocystis, embedded in a tough secretion.
6, 7. Encysted cells of L. macrocystis, with enclosed protoplasm divided into four spores.
8, 9. Transverse division of a nonencysted spindle-cell of L. macrocystis.
i. A colony or " cell-heap " of Labyrinthula vitellina, Cienk., crawling upon an Alga.
2. A colony or " cell-heap " of Chlamydomyxa labyrinthuloides, Archer, with fully

expanded

EXPANDED

network of threads on which the oat-shaped corpuscles (cells) are moving. o, Is an ingested food particle ; at c a portion of the general protoplasm has detached it-self and become encysted.
3 A portion of the network of Labyrinthula vitellina, Cienk., more highly magnified. p, Protoplasmic

mass

apparently produced by fusion of several filaments. p', Fusion of
recalling the Acrasieae. From each cyst ultimately emerges a ~ and for other personal adornments. Lac is a

principal

PRINCIPAL

ingredient single amoebae, or more rarely four (

figs

FIGS

. 6, 7). The saprophyte
Diplophrys (?) stercorea (Cienk.) appears closely allied to this.
Chlamydomyxa (W. Archer) resembles Labyrinthula in its freely branched plasmodium, but contains yellowish chromatophores, and minute

oval

OVAL (Lat. ovum, egg)

vesicles (" physodes ") filled with a substance allied to tanninpossibly phloroglucinwhich glide along the plasmodial tracks. The cell-

body

BODY

contains numerous nuclei; but in its active state is not resolvable into distinct

oval

OVAL (Lat. ovum, egg)

amoeboids. It is amphitrophic, ingesting and digesting other Protista, as well as " assimilating" by its chromatophores, the product being oil, not

starch

STARCH

. The whole

body

BODY

may form a laminated cellulose resting cyst, from which it may only temporarily emerge (fig. 2), or it may undergo resolution into nucleate cells which then encyst, and become multinucleate before rupturing the cyst afresh.
Leydenia (F. Schaudinn) is a parasite in

malignant

MALIGNANT (Lat. malignus, evil-disposed, from maligenus)

diseases of the pleura. The pseudopodia of adjoining cells unite to form a network; but its affinities seem to such social naked Foraminifera as Mikrogromia.
See Cienkowsky, Archiv f. Microscopische Anatomie, 274 (1867), xii. 44 (1876); W. Archer, Quart. Jour. Microscopic Science, xv. 107 (1875); E. R. Lankester, Ibid., xxxix., 233 (1896); Hieronymus and Jenkinson, Ibid., xlii. 89 (1899); W. Zopf, Beitrage zur Physiologie and Morphologie niederer Organismen, ii. 36 (1892), iv. 6o (1894) ; Permed, Archiv fur Protistenkunde, iv. 296 (1904); F. Schaudinn and Leyden, Sitzungsberichte der Koniglich preussischen Akademie der Wissenschaft, vi. (1896).

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